A system for controlling a general crane includes a work instruction system configured to have a schedule for crane operations and various types of work information related to the crane operations, and includes the crane configured to be operated using the work instruction system. The crane is divided into a manned crane which is directly operated by a worker and an unmanned crane which is automatically operated.
The crane travels forward and rearward or laterally based on information (the number, kinds of steel, and sizes of the slabs loaded on an arrived vehicle) received from the work instruction system, thereby carrying the slabs to a destination.
Therefore, in the prior art, when a vehicle on which slabs are loaded arrives, the work instruction system operates a crane such that the slabs can be carried to a relevant destination using work information related to the slabs loaded on the currently arrived vehicle. Here, the crane can simultaneously carry one or more slabs loaded on the vehicle. When slabs are carried, the tongs of the crane must accurately grip the center portions of side surfaces of the slabs for the purpose of safety.
However, in the state in which bending occurred due to uneven cooling of a slab, if the crane grips the corresponding slab based on only work information received from the work instruction system while the amount of the bending is not considered, the tongs of the crane cannot accurately grip the center portion of the side surface of the slab.
Therefore, the slab may fall when it is being carried, so that there are problems in that an expensive product is damaged, and in that danger for a high-risk accident or a disaster always exists.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an apparatus and method for controlling the position of the tongs of a crane depending on the bending of a slab, which rapidly detects the bending state of one or more loaded slabs and adjusts the position of the tongs of the crane, so that the tongs of the crane can accurately grip the center portions of the side surfaces of the slabs to be carried.